[maxgashkov]

Webserver control is never used and must not be used to prove domain ownership. If you're pwned and have to re-point to a server stood up from backup, having registrar relying on someone being able to put up a random file on a compromised machine would be a total security disaster.

[sandeepkd]

On a different note, adding a file on webserver is one of the ACME methods (HTTP-01) to get a SSL/TLS certificate so it is indeed considered as possession method in real world already

[maxgashkov]

You're missing that HTTP-01 challenge grants you no ability beyond what the check has demonstrated, i.e. you have proven that you're able to serve random file from a webserver, so the grant is to allow you to serve them via TLS connection.

There are no comparable _technical_ proof-of-registration methods because all of them would require actual access to registrar control panel and be outright silly ('point the domain to a random nameserver').

So no, proper registrars never use webserver control as means to prove identity or ownership.

[sandeepkd]

> you have proven that you're able to serve random file from a webserver, so the grant is to allow you to serve them via TLS connection.

Its digression from the original topic, still, it goes way far than that, these certificates are signed by a CA that the client devices trusts by the virtue of root certificates installed on the device. If I can some how obtain the SSL/TLS certificate for google then thats a very big deal.

[maxgashkov]

That's why it's very unlikely that you will be able to put a file under google.com/.well-known/acme-challenge

But if you somehow managed to do that, no one in the right mind would argue that you're free to undelegate the domain or point it to a NS you control.

[sandeepkd]

To clarify, my observation is around how it might have happened, not if this is the right way to do it